In a related art, an optical scanner using a Micro-Electro-Mechanical System (MEMS) mirror has been used for a laser printer, a projection image display apparatus or the like. A driving method of the MEMS mirror, there are, for example, a piezoelectric driving method using a piezoelectric element, an electromagnetic driving method using a micro coil or the like, an electrostatic driving method using an electric potential difference between electrodes, and the like. As a driving method of a two-dimensional optical scanner, there are two types, that is, a same-kind driving method and a different kind-driving method. In the configuration of the same-kind driving method, oscillations of the mirror in one direction and in the other direction are generated in the same manner, whereas in the configuration of the different-kind driving method, the oscillations of the mirror in one direction and in the other direction are generated in different manners. In the two-dimensional optical scanner having the configuration of the same-kind driving method, a movement of the optical scanner for the mirror oscillating in one direction and a movement of the optical scanner for the mirror oscillating in the other direction may interfere with each other. Due to this interference, it is difficult to achieve a high accuracy driving control in the two-dimensional optical scanner having the configuration of the same-kind driving method.
FIG. 16 shows a related-art two-dimensional optical scanner 900 having the configuration of the different-kind driving method. The optical scanner 900 includes a fixed portion 910, a movable portion 920 and a spring portion 930. The fixed portion 910, the movable portion 920 and the spring portion 930 are formed by etching process on a crystal substrate. The movable portion 920 includes a mirror 921 and a coil 922. The spring portion 930 is connected with the fixed portion 910 and the movable portion 920, and supports the movable portion 920. The spring portion 930 undergoes torsional vibrations by an electromagnetic force generated by an interaction between an electric current flowing in the coil 922 of the movable portion 920 and a magnetic field MF applied to the movable portion 920. The mirror 921 of the movable portion 920 oscillates in an arrow direction AA by the torsional vibrations. Further, the spring portion 930 undergoes bending vibrations by the piezoelectricity of the crystal, and thus the mirror 921 of the movable portion 920 oscillates in an arrow direction BB. In this way, the mirror 921 of the related-art two-dimensional optical scanner 900 shown in FIG. 16 is driven in the two different-kind driving methods of the electromagnetic driving method and the piezoelectric driving method.
However, since the mirror 921 oscillates in two directions in the two-dimensional optical scanner 900 as shown in FIG. 16, it is required to generate two different types of vibrations of the torsional vibration and the bending vibration in the single spring portion 930. Thus, the two types of vibrations of the spring portion 930 interfere with each other, and therefore, it is difficult to achieve a high accuracy driving control of the two-dimensional optical scanner 900.